This
study demonstrates a highly efficient regiodivergent ligand-controlled
palladium-catalyzed cycloaddition reaction of vinyloxazolidine-2,4-diones
with 1,3,5-triazinanes. In the presence of a diphosphine ligand, the
reaction proceeds via a (5+2) cycloaddition pathway to afford 1,3-diazepin-4-ones
in excellent yields, while using a monophosphine ligand, the reaction
proceeds smoothly via a (3+2) cycloaddition pathway to give imidazolidin-4-ones
in good yields.